Electrode water heating boilers are designed to provide hot water and steam at the expense of heat released by electric current (single- or three-phase one) directly flowing through water. Boilers are used for heating and hot water supply of production and residential spaces, in open as well as close heating systems. They are also used at industrial plants, agricultural plants, and any other facilities which manufacturing processes require hot water of 95 . . . 100 Celsius degrees. The simple design, high reliability, service life, efficiency, and fabricability in mass production as well as the ability of full automation and unattended operation present great advantages of electrode boilers. Their merits also include the potential relative easiness of maintenance of accurate temperature conditions in heated spaces and related to it saving of primary energy resources by consumers. Boilers became proliferated due to those reasons. They also can be used in parallel as hot water circulating pumps.
Among general disadvantages of electrode boilers the geometrically symmetric arrangement of electrodes inside the case, relative to each other, normally in parallel with the longitudinal axes and symmetry axes of the boiler case can be pointed out, which reduces considerably the fabricability of the devices, electrodes, complicates assembly, repair works, and cleaning as the latter can disturb the said symmetry. Besides, such a manner of electrode in-case fastening does not allow flexible purposive changing of convection conditions for liquid flows of different temperatures within the boiler thus impeding the mixing or separation subject to the boiler intended function. In addition, the strictly symmetric arrangement of electrodes creates favourable conditions for uniform deposition of iron oxidation products (rust Fe (OH)2) and foreign particles suspended in the fluid (sludge), which reduces the overall efficiency of electrode system at a rather high rate.
Prior devices can be divided into groups as follows:
Group one. Electrode boilers are known with a true-vertical arrangement of electrodes which longitudinal axes normally either coincide with the boiler symmetry axes (at least for one electrode) or are true-parallel with the boiler symmetry axes (in this case longitudinal vertical ones) as defined in patents: DE2434907 (A1)—Geraet zur regelung der an eine ohmsche last abgegebenen elektrischen leistung 1975 Feb. 13; DE2514524 (A1)—Verfahren and vorrichtung zur verminderung oder vermeidung von krustenbildung an arbeitselektroden 1975 Oct. 9—three-phase boilers; as well as in devices: CA1166296 (A1)—Humidifier electrode shield, 1984 Apr. 24—with an increased current propagation path between the electrodes to reduce the probability of short-circuit by means of a baffle introduced between the electrodes; FR2587449 (A1)—Direct-heating boiler for producing steam and/or hot water, 1987 Mar. 20—with pointed ends of arranged vertically electrodes having their working ends thickened, parallel both with each other and longitudinal symmetry axes of the boiler, and KR101132125 (B1)—A reactor using electrode catalyst for high efficiency steam generator, 2012 Apr. 5—with electrodes fastened at the boiler bottom and arranged upwards in parallel and symmetrically with respect to the boiler. There are many modifications thereof and the following in particular:                a) The said group includes electrode boilers with their electrodes arranged vertically and having washers to maintain the parallel and vertical position of the electrodes in static conditions and all the heating temperature conditions inclusive of dynamic ones: WO9721057 (A1)—Boiler with fast steam generation, 1997 Jun. 12—with one electrode and one washer holding the electrode inside the boiler; U.S. Pat. No. 5,526,461 (A)—Evaporation vessel and electrode arrangement for an electrode evaporator having a dummy electrode 1996 Jun. 11—with one washer on the free ends of electrodes directed vertical-downwards. There are also devices as set forth in patents KR20060093192 (A)—Water heating apparatus using electrodes 2006 Aug. 24—several circumferentially arranged electrodes with one fixing washer; RU43624U1—Multiple electrode for electrode boiler Jun. 10, 2004, with one fixing washer superposed on the upper ends of symmetrically installed electrodes; U.S. Pat. No. 5,384,888 (A)—Vaporizer with electrode positioning 1995 Jan. 24—vertical parallel symmetrically arranged electrodes directed downwards along the symmetric axes, with a taper washer; U.S. Pat. No. 4,748,314 (A)—Device for the rapid vaporization of a liquid 1988 May 31—one electrode having on its free end a washer holding it in the boiler case; GB2444369 (A)—Electrode heater for liquid 2008 Jun. 4—with a sectional washer on vertical electrodes parallel with the boiler longitudinal axis; CN2306395 (Y)—Electrode device for generating steam 1999 Feb. 3—multi-sectional washers on parallel horizontally installed electrodes, which sections are equally spaced along the whole length of the electrodes;        b) Opposed arrangement of electrodes parallel with the boiler symmetric axes and each other, for example, WO8302710 (A1)—Current distribution for glass-melting furnaces 1983 Aug. 4—vertical upper and lower electrodes; RU2137029—Electrode boiler water heating, 26 Dec. 1997—opposed upper and lower electrodes offset with respect to each other in parallel with their longitudinal axes, arranged symmetrically in the case;        c) Boilers with electrodes installed in them in parallel and symmetrically to each other and boiler case can also be attributed to the group in question; electrodes having protective covers. Those devices are such as U.S. Pat. No. 6,263,156 (B1)—Recycling of air humidifier cylinders 2001 Jul. 17—vertical electrodes having protective covers; CN102439358 (A)—An electrode boiler 2012 May 2—with covers on vertically downward symmetrically arranged electrodes; U.S. Pat. No. 5,454,059 (A)—Evaporation control adaptor sleeve for vaporizer electrode 1995 Sep. 26—inclined conical cover on electrodes; U.S. Pat. No. 6,263,156 (B1)—Recycling of air humidifier cylinders 2001 Jul. 17—vertical electrodes having protective covers; P61134503 (A)—Electric type once-through boiler 1986 Jun. 21—protective covers on electrodes made as mating cylinders different in their diameters;        d) Various kinds of bushings superposed on round electrodes to improve the basis insulating properties, for example, in accordance with patent DE2732683 (A1)—Elektrodendampferzeuger 1979 Feb. 1—multiple electrode with bushings;        e) Devices having their electrodes of different heights can be ranked in the group of vertical symmetric electrodes, for instance, WO8301101 (A1)—Steam generator 1983 Mar. 31; RU1638444, steam generator, Apr. 4, 1989—with measuring electrodes of different heights; KR20020013018 (A)—Method and apparatus for controlling operation of electric steam boiler 2002 Feb. 20—active electrodes of different heights; DE2456665 (A1)—Elektrode fuer wasserstrahl-elektrodendampferzeuger 1976 Aug. 12—honeycomb active electrodes of different heights;        f) Electrodes are also used, which sections are non-circular, for example, truncated circle sections—KR101132125 (B1)—A reactor using electrode catalyst for high efficiency steam generator, 2012 Apr. 5; or sections in the form of any other geometric figures: U.S.2008279539 (A1)—Steam Generator Comprising a Swirling Device, 2008 Nov. 13—vertical electrodes of trapezoidal section, parallel with the longitudinal axis; CN101952654 (A)—Segmented rapid heating of fluid, 2011 Jan. 19—sectional plate electrodes; KR20030090894 (A)—Simple steam generator, 2003 Dec. 1—grooved plate electrodes.        
Group two. Used electrodes in the shape of entirely different geometric figures.                a) Cylindrical coaxial electrodes: RU2168875—electrode for electrode liquid heater, 28 Dec. 1999; RU2168876—electrode for electrode water heater, 28 Dec. 1999—multilayer electrodes; similar to the above U.S. Pat. No. 4,812,618 (A)—Electrode boiler and an insulator therefor, 1989 Mar. 14—electrode with heat-conducting electric insulator; RU12637U1—electrode liquid heater, 4 Aug. 1999—electrodes in the form of hollow cylinders, symmetric in their cross-sections, equal in angles circular sections in the form of regularly alternating electroconductive and non-conductive sections; RU16419U1—electrode liquid heater and electrode (alternatives), 29 Feb. 2000—coaxial electrodes one of which is a cylindrical case accommodating the internal electrode so that the longitudinal axes of the case and electrode coincide; RU2189541 electrode liquid heater, 11 Apr. 2000—coaxial electrodes; KR20010084150 (A)—Electric boiler 2001 Sep. 6—slotted coaxial cylinders; JP8261689 (A)—Preventing method of generation of extraneous matter in water storage tank and waterstorage tank with executing device of said method 1996 Oct. 11—coaxial electrodes; U.S.2009226356 (A1)—Device and Method for Evaporating a Reactant, 2006 Oct. 2—horizontally arranged coaxial cylinders; CA2163932 (A1)—Method and apparatus for preventing the development of scale deposits in a water tank 1996 Jun. 2—concentric coaxial electrodes; GB2183802 (A)—Device for the fast generation of steam vapor 1987 Jun. 10—the electrodes are in the form of coaxial bowls with angled walls but being arranged along the boiler symmetric axis and symmetric themselves; WO0011914 (A1)—On-demand direct electrical resistance heating system and method thereof for heating liquid, 2000 Mar. 2—concentric electrodes arranged symmetrically with respect to each other; RU2209367—Electric boiler, 22 Nov. 2001—coaxial perforated electrodes arranged in aligning;        b) Bent, twisted, spiral electrodes having sections deviating from one direction, for instance, SU303475 Steam generator, 2 Sep. 1968—twisted electrode; SU379995—screw electrode, 1973 Apr. 20; WO8800316 (A1)—Steam generator for analytical instruments, 1988 Jan. 14—a combination of electrode helical section and vertical sections directed downwards; SU465521—Electric steam generator,—an electrode in the form of a straight spiral totally symmetric with respect to the boiler vertical symmetry axis; WO9318338 (A1)—A water tank for heating water preferably in a vending machine, 1993 Sep. 16—an electrode in the form of an inclined spiral with an inclined section but with its turns arranged symmetrically with respect to the boiler longitudinal vertical axis; WO0175360 (A1)—Household steam generator apparatus, 2001 Oct. 11—a coiled electrode; RU2324859—Electric steam generator, 4 Dec. 2006—electrode in the form of a symmetric spiral with central vertical terminal; WO9917056 (A1)—Process for restoring the level of water in boilers of steam generating machines 1999 Apr. 8—bent by 90 degrees electrode, and CN1082683 (A)—Efficient method for producing steam and seven kinds of thermal electric appliance of efficient steam 1994 Feb. 23; WO0031467 (A1)—Device for instantaneously producing steam 2000 Jun. 2—a combination of horizontal and vertical electrodes; WO9506399 (A1)—Heating element 1995 Mar. 2—vertical U-electrode; FR2593890 (A1)—Improved electric steam generator with water jets 1987 Aug. 7—one bent electrode angled with respect to the case longitudinal axis; WO9013771 (A1)—Steam generator 1990 Nov. 15, WO9836215 (A1)—Steam generator 1998 Aug. 20—horizontal U-electrodes;        c) Electrodes of other shapes, for example, SU1174683—Electric liquid heater, 27 Jul. 1983—one of the electrodes designed to be the case concurrently is made in the form of de Laval nozzle; SU879184—Electrode water heater, 30 Jan. 1980—piston-type electrode with a cone.        
Group three. Inclined fastening of electrodes inside the case or partially inclined sections of electrodes:                a) Cone electrodes, for instance, as defined in patents: RU1064083—Electrode heater, 19 May 1982; RU1250791—Electrode heater, 14 Mar. 1985—electrode in the form of a symmetric inverse cone symmetrically arranged inside the case; RU1333992—Electrode heater, 1 Aug. 1985—the central electrode in the form of cone, directed downwards; U.S. Pat. No. 5,940,578 (A)—Water evaporation apparatus 1999 Aug. 17—angled walls of a chamber accommodating a symmetrically arranged electrode; U.S. Pat. No. 6,072,937 (A)—Steam generator 2000 Jun. 6—cone electrode, its longitudinal axis coinciding with the boiler vertical axis;        b) Inclined electrodes RU2037088—Three-phase current electric water heater, 30 Jun. 1992—plate trapezoidal inclined electrodes but arranged symmetrically with respect to the case symmetric axes; GB2178834 (A)—Steam generator 1987 Feb. 18—flat electrodes converging upwards but arranged true-symmetrically with respect to the boiler vertical longitudinal axis; GB2190989 (A)—Electrically heated steam generator 1987 Dec. 2—bent-down auxiliary surfaces; DE2644355 (A1)—Elektrodampferzeuger 1978 Mar. 30—inclined symmetric entry of electrodes but the electrodes are not inclined themselves and meet the boiler symmetry; JP4324001 (A)—Power generation plant 1992 Nov. 13—symmetric electrodes arranged along the cone generatrix; JP60038501 (A)—Electric type steam generator 1985 Feb. 28—inclined sections of vertical electrodes; JP60108602 (A)—Electric type steam generator 1985 Jun. 14—conical parts of cylindrical electrodes;        c) Other types of inclined components, for example, CA1244864 (A1)—Electrode configuration for a high voltage electrode boiler 1988 Nov. 15—inclined channels for heated liquid; JP2002317902 (A)—Nozzle assembly for electrode type electric boiler 2002 Oct. 31—tilted nozzle; CN201145263 (Y)—Electrical heating device of water 2008 Nov. 5—rotating plate electrodes; RU2225569—Steam generator, 30 Aug. 2001—branching electrode, but at the same time symmetrically arranged inside the case and forming symmetrically arranged branching sections.        